Head for mixing and ejecting interacting liquid components, for molding plastic materials

Abstract

Disclosed herein is a head for mixing and ejecting interacting liquid components, in particular for molding articles made of plastic material. The head comprises: a mixing chamber that communicates with a discharge duct, and a first and at least a second duct for infeeding the individual components, the orifices of which open into the mixing chamber; the latter being placed laterally with respect to the discharge duct and its axis forming an angle with the axis of the discharge duct.

What is claimed is: 
     
       1. A head for continuously mixing and ejecting interacting liquid components into a mold for molding articles made of plastic material, comprising in combination: a body defining a mixing chamber for the components; a discharge duct having an outlet; at least a first and a second infeed duct for injecting individual components into said mixing chamber for a predetermined time period; exit port means for establishing fluid communication between said infeed ducts and said discharge duct, said infeed ducts being provided with outlet orifices that open into said mixing chamber close to said exit port means; and piston means for controlling fluid communication between said infeed ducts and said discharge duct outlet so that fluid communication is established therebetween during substantially the entire predetermined time period when said infeed ducts are injecting components into said mixing chamber so that injected components flow continuously out of said mixing chamber through said discharge duct and are thoroughly mixed during their passage through said discharge duct, said mixing chamber forming an angle of substantially 90° with said discharge duct and having a length shorter than and a volume less than that of said discharge duct so that components injected into said mixing chamber mix with each other and overflow into said discharge duct in a swirling flow. 
     
     
       2. A head according to claim 1, in which said mixing chamber and said discharge duct are axially extending, and in which said mixing chamber, in a plane perpendicular to its axis, has a cross-sectional area different from a corresponding cross sectional area of said discharge duct. 
     
     
       3. A head according to claim 1, comprising at least a first and a second duct for recycling the individual components, the infeed ducts being positioned between said recycling ducts and said discharge duct, and said piston means comprising a recycling valve of the slide type having piston means able to slide in said mixing chamber, said piston means being movable between a first position in which fluid communication between said mixing chamber and said discharge duct is blocked and respective ones of said infeed and discharge ducts are in fluid communication with each other, and a second position in which said mixing chamber and discharge duct are in fluid communication and fluid communication is blocked between said infeed and recycling ducts. 
     
     
       4. A head according to claim 3, further comprising a cleaning member mounted for axial movement in said discharge duct, said cleaning member being movable into a recessed position in which the exit port of said mixing chamber to said discharge duct is positioned between said cleaning member and an outlet of said discharge duct; and a switch-controlled cylinder for operating said recycling valve, said switch being actuated by movement of said cleaning member into said recessed position. 
     
     
       5. A head according to claim 1, further comprising a cleaning member mounted for axial movement in said discharge duct, said cleaning member being movable into a recessed position in which the exit port of said mixing chamber to said discharge duct is positioned between said cleaning member and an outlet of said discharge duct so that components flow continuously from said infeed ducts into said mixing chamber, flow through said mixing chamber into said discharge duct, and are ejected from the outlet of said discharge duct. 
     
     
       6. A head for continuously mixing and ejecting predetermined variable amounts of fluid materials, comprising a body defining a mixing chamber; a discharge duct having at one end an outlet portion for ejecting a mixture, said discharge duct having an inlet communicating with said mixing chamber and having an axis extending transverse to an axis of said mixing chamber; a cleaning member able to slide in the discharge duct between recessed and extended positions, in said recessed position said duct inlet being in fluid communication with said duct outlet portion and in said extended position said cleaning member blocking fluid communication between said duct inlet and said duct outlet portion; a first double acting cylinder for moving said cleaning member between said recessed and said extended positions; a first and a second duct opening into said mixing chamber for infeeding individual components, said infeeding ducts being positioned in close proximity to said duct inlet so that mixing action initiated in said mixing chamber continues in said discharge duct; a first and a second duct for recycling the individual components from said mixing chamber; and a slide valve movable between a first position in which selected ones of said infeed and recycling ducts are in fluid communication with each other and fluid communication is blocked between said infeeding ducts and said duct inlet, and a second position in which said infeeding ducts are in fluid communication with said duct inlet and fluid communication is blocked between said infeeding and said recycling ducts; a second double acting cylinder for controlling movement of said slide valve between said first and said second positions; and operating link-up means between said double acting cylinders for moving said slide valve from said first to said second position after said cleaning member has been moved from said extended position towards said recessed position so that said infeeding ducts, mixing chamber, and discharge duct are in fluid communication with each other during substantially the entire period during which individual components are fed into said mixing chamber so that the components overflow from said mixing chamber into said discharge duct, said operating link-up means comprising a switch operatively associated with said first double acting cylinder, an electrovalve actuated by said switch, a supply circuit of said second double acting cylinder being connected to said electrovalve. 
     
     
       7. A head according to claim 6, wherein the axis of said mixing chamber is perpendicular to the axis of said discharge duct. 
     
     
       8. A head according to claim 6, wherein the cross-sectional area and volume of said mixing chamber are less than the cross-sectional area and volume of said discharge duct. 
     
     
       9. A head according to claim 1 or 6, wherein the length of mixing chamber is very limited compared with the length of the discharge duct.